REPORT FOR THE UNIVERSITY OF HAWAI’I AT HILO MARINE OPTION PROGRAM

Trout, Salmon, and Shrimp:

Research Experiences with the Fish Wildlife and Parks in Montana

Ashlin Stahlberg

Marine Science Department

University of Hawai’i at Hilo

MOP Advisor

Professor Lisa Parr

Marine Science Department University of Hawai’i at Hilo

2-10-15

Table of Contents

Abstract 1

Introduction 1

Objectives 2

Methods and Materials 2

Results and Discussion 4

Conclusion 11

References 12

Trout, Salmon and Shrimp:

Research Experiences with the Fish Wildlife and Parks in Montana

Abstract:

The ecosystem of Northwest Montana is under threat from human interaction. To understand the

negative effects humans have had on the unique ecosystem, the Fish, Wildlife, and Parks

monitors the land and water resources. The internship I participated with the Montana state Fish,

Wildlife, and Parks was located in the Flathead Valley, Montana. Fish, Wildlife, and Parks has

many different responsibilities within the state, overseeing hunting, fishing, and recreational use

of state land. I worked with the Fisheries department, where the main responsibilities of my

internship involved analysis of substrate samples, using electrofishing to conduct population

surveys, checking fish traps, and working with the Sekokini Fish Hatchery. Plankton tows were

also conducted to check the population of the invasive Mysis shrimp. Substrate samples from

streams were analyzed to gauge the health of those streams for fish eggs because the percentage

of small grains to larger gravel determined the likelihood of fish eggs to survive to emergence.

The majority of streams surveyed were good habitat for fish spawning and egg survival.

Electrofishing surveys were used to observe the population of the native and endangered Bull

Trout (Salvinius confluentus). Fish live traps also helped track the movements of native species

such as Bull Trout and Westslope Cutthroat Trout, as well as the spread of invasive species. Fyke

traps were set in Lake Mary Ronan to investigate the population of illegally introduced Northern

Pike (Esox lucius). No pike were captured in these traps, so their numbers and distribution

throughout the lake are still uncertain. With Sekokini Fish hatchery I assisted in spawning native

Westslope Cutthroat trout (Oncorhynchus clarki lewisi) and monitored the condition of the

maturing eggs. Through this work I learned about management techniques and methods to

control invasive species.

Introduction:

The ecosystem of lakes in the Northwest United States is threatened by man-made interference.

Dams and the introduction of non-native species have negative effects on fish and other wildlife

in the area, from bears to eagles (Muhlfeld et al. 2012, Spencer 1991). Throughout the Northwest

United States the populations of native species such as cutthroat trout (Oncorhynchus clarkia

lewisi) and the endangered bull trout (Salvelinus confluentus) are threatened by non-native

species including lake trout (Salvelinus namaycush) and rainbow trout (Oncorhynchus mykiss)

(Muhlfeld Giersch and Marotz 2012, Peterson 2004, Wiegel 2003). Native bull trout can be

negatively affected by human building and development in an area (Dunham 1999).

Human manipulation of the food chain has created problems for other native species in the

Northwest area also. The arrival of Opossum shrimp, Mysis, which was introduced with the

intent of boosting salmon populations in Flathead Lake, Montana, ended up destroying the

population of salmon. The shrimp were intended to be a food source for the salmon, but, despite

the best motives, the introduction resulted in the Mysis shrimp consuming the zooplankton and

removing the salmon’s food sources. The disappearance of the salmon disrupted the population

of bears and resulted in the mass movement of the eagle population, which previously had fed on

the salmon (Spencer 1991). A further threat to native species in the Flathead area is the

hydroelectric dam on the Flathead River. This dam changes normal seasonal flooding patterns of

the river, which can have negative effects on the trout populations (Muhlfeld et. al. 2012).

While humans have had a mostly negative impact on the ecosystem, it is possible to prevent and

mitigate those effects. As part of understanding populations of fish, especially endangered

species, it is necessary to investigate the quality of spawning habitats. Taking substrate samples

is one way to determine the quality of spawning streams for trout. The percentage of fine

sediment to coarser gravel determines the amount of oxygen that will reach the developing eggs

in the gravel and therefore the amount of eggs that will survive to emergence.

Because of the significant effects humans have had on the ecosystem it is important to monitor

the populations of both native and non-native species and their ecosystem. This information will

be used to write fishing regulations and inform future policies of land use. As a summer intern

with Fish, Wildlife, and Parks in Kalispell, Montana, I helped monitor these populations and

conduct research about their habitats.

Objectives:

My goals through this internship were to gain experience in analyzing substrate samples, in

electrofishing, tagging, and other population survey techniques, as well as learn about

monitoring and the control of invasive species.

Methods and Materials:

Study site:

I worked with the Fisheries department of the state Fish, Wildlife, and Parks, (FWP) in

the Flathead Valley of Kalispell, Montana. The goal of FWP is to preserve the ecosystem

for future generations to enjoy and to manage responsibly the wildlife and natural

resources. There are several major branches of the FWP, which are Wildlife, Fisheries,

and Enforcement. The physical location includes a large office where the public can

come to learn about the ecosystem, get information on hunting and fishing permits; as

well as a large garage area where the boats, vehicles, nets, live traps, and other equipment

were stored. The facility also included a small lab equipped with several types of

microscopes, scales, vials, water equipment, and other instruments. The responsibilities

of the whole organization include writing hunting regulations, fishing regulations, public

education, research, and enforcing regulations. The state is divided into seven regions and

I worked in Region 1. The management area includes Flathead Lake, all forks of the

Flathead River, and the Hungry Horse reservoir on the South Fork, Jewel Basin, and

Swan Lake drainage. The terrain is mountainous covered in pine forest with high alpine

lakes.

Fig. 1 Map of the state of Montana with different FWP regions labelled. Region 1 is the

Flathead region.

My responsibilities at Fish, Wildlife, and Parks involved many different projects with

multiple persons within the Fisheries department. I was an intern with Tom Weaver,

research specialist. I also worked with Jon Cavigli, Scott Hawxhurst, Leo Rosenthal, and

Amber Steed as part of the Fisheries Department. Analysis of substrate samples, checking

fish and fry traps, setting gill nets, working with Sekokini Fish Hatchery, mounting fish

scales, conducting surveys for Mysis shrimp, bathymetric surveying, posting signs to

educate the public, electrofishing, and data entry were all part of my experience. During

the internship I documented the work done with photographs and journal entries. I have a

record of the lakes and methods used to sample them, as well as photographs of the sites.

Substrate Analysis:

As part of the effort to monitor the quality of spawning streams, substrate samples taken

needed to be analyzed by sorting the samples by grain size by drying each sample. I did

all of this by removing the samples from their plastic bags, spreading them on broad trays

and placing them in the oven to dry overnight, then putting each sample through a series

of progressively smaller sieves. The gravel samples would be swept into stacks of

gradually smaller sieves to sort the samples by size. The sieves would be shaken by

machine for 12 minutes to make sure the gravel was settled into the correct size. Each

size of gravel was weighed and recorded. The percent composition of fine grains (under

6.35 mm) to coarser sediment provides the ability to predict the survival-to-emergence

percentage of fish eggs.

Population surveys:

Population estimates and surveys were an important part of my internship. The three

different types of population surveys: electrofishing, fish traps, and gill nets. Population

estimates of fish were conducted in several areas around the Flathead Valley by

electrofishing. The east side of Hungry Horse Reservoir and the Jewel Basin/ Swan Lake

area were places where I assisted in taking population estimates using backpack

electroshockers. An area of the stream 150 yards was measured off and a block net was

placed at the downstream end of the area. Then we proceeded downstream and collect all

the fish stunned by the shock. My supervisor would carry the backpack electrofisher. The

backpack had a long rod attached, which the person would hold and run through the

water to send out the electric shock. I would walk in front to catch the stunned fish and

carried them in a bucket of water. After we shocked the entire section we weighed the

fish, and I recorded the length, mass, and species of each fish we caught.

Another kind of electrofishing was done with a boat. This kind of electrofishing was used

in rivers for similar purposes, to monitor species population and diversity. The electric

current was sent into the water through long wires off the front of the boat. This method

was also used in Lake Mary Ronan to attempt to find a population of illegally introduced

Northern Pike.

Fish traps were set on several streams to monitor fish migration and hybridization. The

traps were essentially mesh cones spanning the width of the stream that led into mesh

boxes. The boxes were about 3-4 feet across and the fish would swim in and be unable to

escape. Westslope Cutthroat Trout and Rainbow trout caught in these traps in the streams

of the North Fork Flathead River drainage were tagged and a DNA sample was taken.

The DNA was sent to a lab to determine if the fish was a Cutthroat/Rainbow hybrid. I

assisted in checking the fish traps and periodically cleaning them of debris. Fyke traps

are another type of fish trap that was used on Lake Mary Ronan to catch invasive

Northern Pike. I assisted in setting, retrieving, and repairing these traps, as well as

recording the fish caught in them.

Gill nets were set in lakes, such as Beaver Lake, to monitor the population of Rainbow

trout and Kokanee salmon. I assisted in setting these nets and then pulling them out again

after a set amount of time, usually overnight. Then we untangled the fish from the nets so

they could be counted, weighed, and recorded.

Populations of some plankton species are also monitored. Mysis shrimp are a problem

species in Northwest Montana. Since Mysis are firmly established, FWP checks their

population by conducting plankton tows. On Swan Lake I helped take the survey by

pulling the plankton nets and counting the Mysis collected.

Fish Hatchery:

Sekokini Fish Hatchery is part of Fish, Wildlife, and Parks, so I also spent time there

helping with the spring spawning of Westslope Cutthroat trout. Part of my job was

making sure the eggs were clean and healthy by rinsing them with an iodine solution and

picking out bad eggs. I also fertilized the eggs by mixing the roe from the adult females

with seed from the males. This was done with different parents in each set of eggs to

ensure genetic variability.

Mounting Fish Scales:

I mounted fish scales, which involves making an impression of the scale on a plastic

sheet. This was done for several different species including Kokanee Salmon and Large

Mouth Bass taken from several different locations. First I would take the scales from the

sample envelope and place them on an acetate sheet, then put that sheet between two

metal sheets and compressed at high temperatures in a press for 20 seconds. Then I would

remove the scales, replace them in the envelope, and check the impression left under a

microfilm reader.

Bathymetry:

In Meadow Lake a bathymetric survey was conducted to create a topographical map of

the bottom of the lake. We used a canoe and a line pattern to take depth readings of most

of the bottom of the lake. We used a small depth finder, about the size of a flashlight.

This information was sent to a cartography center in Helena, which took the raw data and

generated a bathymetric map.

Results and Discussion:

I was the most heavily involved with the substrate analysis project. Understanding the substrate

component of spawning streams is important because too much fine sediment hinders water

flow, essentially suffocating the eggs. In total, 14 different streams were surveyed and each

stream had 12 samples taken from different areas along its length. We found most streams had a

percentage under 40% by weight of fine grains under 6.35 mm. The substrate sample analysis

produced encouraging results. Almost all of the streams surveyed in and around the Flathead

drainage system had good percentages of gravel composition to allow water flow and fish eggs

to survive.

Fig. 2: Substrate Sample analysis equipment. Left: mechanical shaking apparatus. Middle: Sieves

with a sample. Right: Stack of graduated sieves.

Fig. 3: A chart of mass of all sizes of grains within the 12 different samples from Big Creek. It also includes the

total percentages of each grain size. The median highlighted is the mean percent by mass of all the grains less than

6.35 mm in the streams.

Electrofishing population surveys were intended to monitor the population of first and second

year fry living in the stream. These population surveys were encouraging in that they

demonstrated that the population had not significantly changed since the last year’s surveys. The

population of cutthroat and bull trout young remained stable. The different population survey

methods each had different advantages. With backpack electrofishing, we were surveying small

streams and recording the small first and second year fry. When fish traps were set we were

monitoring the movement of fish up and down specific streams and the spread of hybridization.

Gill nets were only used sparingly in specific lakes because this is a method lethal to the fish.

Gill nets were used in areas where it was known to have high numbers of invasive fish species

and were used to get a wide cross section of the different species within a lake.

Fig. 4: A backpack electroshocker and a block net, used to stop the fish from escaping

downstream.

The other methods used to measure population spread and fish migration were fish traps. There

were several different kinds of traps used. One kind was set in streams to catch migrating

Westslope cutthroat trout and bull trout. While working with the Fish, Wildlife, and Parks I

learned certain areas of Montana still had pure Cutthroat Trout, while other areas had Westslope

Cutthroat and Rainbow hybrids. Initial research possibly indicated that hybridized species were

less hardy than the pure species. However, further research is in progress and these traps helped

us measure the spread of hybridization.

A problem in Northwestern Montana is the introduction of new species by people, usually

intentionally. Some sport fishermen wish to catch a favored species in their local lake and will

catch and transport live fish to start in that lake. Unfortunately, this kind of “bucket biology” can

devastate the existing ecosystem of that lake. The fyke traps were set for several weeks, but no

Northern Pike were found. It is a possibility that these traps were set in poor pike habitat, but it is

more likely that the hunting strategy of pike does not led itself well to capture in fyke traps. Pike

are ambush predators and will rarely venture out of hiding without some kind of prey within

reach. The fyke traps are designed to catch mobile fish that are more active swimmers.

Electrofishing using a boat was also tried to catch pike, however, the large area of Lake Mary

Ronan made this unsuccessful.

Fig. 5: Lake Mary Ronan

As part of Fish, Wildlife, and Parks, I also worked with the Sekokini Fish hatchery. While there I

helped monitor the condition of the eggs. Sekokini raises genetically pure Westslope Cutthroat

Trout for release back into the wild in an effort to reverse hybridization. Taking care of the

incubating fish eggs involves periodically rinsing them in an iodine solution to prevent the

growth of mold. If the mold gets prevalent enough it will kill all the eggs within a batch, so

cleaning the eggs is important. The iodine solution toughens the outside of the eggs so they will

be able to stand handling when being cleaned.

Fig 6. Eggs in an iodine bath Fig. 7: Eggs ready to hatch in an incubator

Mounting fish scales on an acetate sheet makes a clear impression of the scale. Fish scales grow

in rings, much like a tree, and the age of the fish can be determined from viewing these

magnified scales. I did this for several different species of fish that were caught at differing

locations to see what the average age was for that species. This combined with the size of the

fish when it was caught gives a good estimate of how large a fish can grow in a year in a given

area.

Fig. 8: An acetate sheet with scale impressions on it from a Kokanee Salmon.

Fig. 9: A magnified version of the scale impression.

Mysis Shrimp were introduced to the Northwest Montana lakes to improve salmon populations,

but ended up having the opposite effect. Now that the Mysis are firmly established, the Fish

Wildlife and Parks conducts plankton tows to measure their population numbers and spread. On

Swan Lake we conducted six tows, three each at two specific locations. I counted the number of

shrimp found, which would be compared to the number of shrimp found during other years.

Fig. 10: Mysis Shrimp from Swan Lake

Several small lakes around Flathead Lake have not been surveyed for habitat suitability. A

population survey of cutthroat trout in Meadow Lake had been conducted earlier in the year.

The depth of the lake and its other features would complement the information on the trout

population found in the lake. (See Fig. 10)

Fig. 11: Bathymetric

map of Meadow Lake

The work that I did in this freshwater environment will be applicable to the marine environment

in several ways. The experience in conducting scientific surveys, which can later be applied to

marine science, was invaluable. The different ways of monitoring and controlling invasive

species can be directly applied to the marine environment. Understanding how populations are

affected by different factors such as fishing, human pollution, and invasive species is a huge part

of responsible use of our oceans. Learning about a freshwater environment was helpful to

making contemporary issues in marine science applicable.

The best part of this research was working outside and being in the field. It was physically

challenging at times because many of the locations we surveyed were fairly remote and there

was a lot of hiking involved. It was a great experience and I gained a deeper understanding of the

Montana ecosystem than I thought possible in just a few months. The most important thing I

learned was how much there is still to learn.

References:

Dunham JB, Rieman BE (1999) Metapopulation structure of bull trout: Influences of physic,

biotic, and geometrical landscape characteristics. Ecol Appl 9 (2): 642-655

Muhlfeld CC, Giersch JJ, Marotz B (2012) Seasonal movements of non-native lake trout in a

connected lake and river system. Fisheries Manag Ecol 19 (3): 224-232

Muhlfeld CC, Kotter JD, Miller J, Geise D, Tohtz J, Marotz B (2012) Assessing the impacts

of river regulation on native bull trout (Salvelinus confluentus) and westslope cutthroat trout

(Oncorhynchus clarkia lewisi) habitats in the Upper Flathead River, Montana, USA. River

Res Appl 28 (7): 940-959

Peterson DP, Fausch KD, White GC (2004) Population ecology of an invasion: Effects of

brook trout on native cutthroat trout. Ecol Appl 14 (3): 754-772

Spencer CN, McClelland BR, Stanford JA (1991) Shrimp stocking, salmon collapse, and

eagle displacement. BioScience 41 (1): 14-21

Stribling JB, Jessup BK, Feldman DL (2008) Precision of benthic macroinvertebrate

indicators of stream condition in Montana. J N AM Benthol Soc 27 (1): 58-67

Weigel DE, Peterson JT, Spruell P (2003) Introgressive hybridization between native

cutthroat trout and introduced rainbow trout. Ecol Appl 13 (1): 38-50